RFR: FinalEvac pause to turn off evacuation

[Aleksey Shipilev]

On 03/15/2018 02:56 PM, Roman Kennke wrote:
> Take this webrev instead:
> 
> http://cr.openjdk.java.net/~rkennke/final-evac/webrev.01/

*) I now remember trying this, by renaming VMOp_ShenandoahVerifyHeapAfterEvacuation: it is not
needed in itself anymore, and you can invoke Verifier from ShenandoahFinalEvac.

*) New enum constants are misplaced:

 67     final_mark_gross,
 68     final_mark,

 70     final_evac_gross,
 71     final_evac,

The logging would print:

  Pause Final Mark
  Pause Final Evac
    <Final Mark subtasks>

Thanks,
-Aleksey